What is all this hardware do...?

Bushido Philosopher · Post by **Bushido Philosopher** » Wed Aug 21, 2002 10:44 pm

I came up with a question that I haven't really had gotten an answer to. Places like doom9.net and digital-digest don't really explain the hardware part of video.

So what the hec does a video card do or a graphics accelerator do?
If you now a good recource site then i'd be happy if you posted a link.

I haven't really been able to find anything that really gives out a clear explanation...

jbone · Post by **jbone** » Wed Aug 21, 2002 10:45 pm

video card = pop it into your computer and you can see stuff on a monitor

"accelerator" = you can do cool $h!t like 3D

It gets much more complicated than that, but that's basically what they are.

Bushido Philosopher · Post by **Bushido Philosopher** » Wed Aug 21, 2002 10:48 pm

well, i was more looking for a more detailed response. that's why i asked for a site or something.

i wanna know ALL the hardware involved.

klinky · Post by **klinky** » Wed Aug 21, 2002 10:51 pm

Most monitors now adays, and practically all monitors in the old days were analog, built off the technology basically used in tvs. Which is analog.

Computers are digital. The first graphic cards out there were just a way to convert a digital array into something a analog monitor could use. On the card there is a Digital To Analoc convert a DAC, which does that.

That's basically what a video card does.

Later on things like accelerated 2D & 3D were added to video cards.

In terms of video editing, the video card doesn't play a big role in actually processing video. The CPU is the main thing used when it comes to video editing. The CPU has to read the video data, decode it and then send it out to the video card so it can then transfer it to your monitor.

Check this link out for alot of info on computers in general, but there is a large video card section in there. Though most of the stuff they talk about isn't used much anymore, it's helpful to know anyways

http://zeus.eed.usv.ro/misc/doc/upgrep/

~klinky

trythil · Post by **trythil** » Thu Aug 22, 2002 12:01 am

klinky wrote: In terms of video editing, the video card doesn't play a big role in actually processing video. The CPU is the main thing used when it comes to video editing. The CPU has to read the video data, decode it and then send it out to the video card so it can then transfer it to your monitor.

Actually, it depends on what output method you're using, and therefore the video card can play a role in video speed.

CPU speed plays a large part in decoding, yes. But when it comes to displaying that data on-screen, several options exist. Some video players (and video editors) give you the option of rendering video frames as OpenGL textures and rendering them on a plane, and then viewing that plane with an orthogonal camera. For example, both Xine and mplayer offer that option. (Not sure about anything on Windows.) In this case, video hardware speed is a factor.

If you have a really slow video card, then any video output system that tries to gain direct access to the display buffer (which includes an option present in nearly every modern player) will be slow.

Video editors, as they have the same choice of video output methods as video players do, also are influenced by this.

More drivel:

Some video cards (e.g. stuff from ATI) also include on-board circuitry to aid in producing a better video image. You'll see phrases like "accelerated DVD playback", "improved video playback quality", etc. on video board boxes. Sometimes it's just marketing drivel, but sometimes it really does refer to something significant.

--

One more thing: The video card plays another role when it comes to, well, viewing video, which obviously has a lot to do with video editing.

Video cards represent color using only so many bits per pixel -- the maximum these days, for all practical purposes, is 24-bit color. (32-bit color doesn't give you any more colors.) 24-bit color, three components (RGB) = 8 bits per pixel. When you start doing complex blends, you can lose some color fidelity. (Of course, add more bits, like the Matrox Parhelia does, and you lose less fidelity.)

This is currently more of a problem in realtime 3D than it is in video editing (as high-level video editors internally maintain large bit-spaces for mathematics on color values), but it's still a video processing issue, nonetheless.

--

God knows I'm wrong on half of this, and I probably didn't answer the question in the first place.

klinky · Post by **klinky** » Thu Aug 22, 2002 12:27 am

Basic operations of a video card is to convert the digital array to something analog that the monitor can work with.

The other stuff Trythil is trying to CONFUSE you with

would be more on the line of "accelerators", which you did ask about. But it's harder to explain about "acellerators" since there are different kinds. Though you can sorta thing of it as this, if the card has "MPEG2" acceleration, then it accelerates just that "MPEG2" playback, same for 2D or 3D. To really understand how it accelerates something you need to know about what it's accelerating.

Usually it's a special processor on the card that is meant to do only things for a certain function like 2D, 3D or DVD playback.... So unless you know how MPEG2 is encoded/decoded or 3d/2d programming you're not going to be able to grasp fully *HOW* it makes stuff faster... there that's what klinky was trying to say...

Of course I don't understand half the stuff either so

Heheh

~klinky

trythil · Post by **trythil** » Thu Aug 22, 2002 1:50 am

klinky wrote:Basic operations of a video card is to convert the digital array to something analog that the monitor can work with.

Yes, and that digital->analog conversion involves some of the stuff I wrote.

Video acceleration was also something mentioned in the original post.